DE102006006204A1 - Tool e.g. application nozzle, controlling and guiding arrangement, has retainer that is not represented and diffusably represented in such a manner that operating area is analyzable around work piece - Google Patents

Abstract

The arrangement has a mirror (17) arranged in a pupil (15) of lenses (10a, 10b), where an image optical path is deviated by the mirror. A tool is centrically arranged in an image area, and a retainer (6) within the optical path is arranged either approximately centrical to the optical path, directly in the pupil of the lenses or close to the pupil. The retainer is not represented and diffusably represented in such a manner that an operating area (8) is analyzable around a work piece. An independent claim is also included for a method for assembling or gripping an arrangement for controlling operating performance of a tool and guiding a tool.

Description

The The invention relates to a device for optical guidance of a Tool and / or for optical online control of the work result of a tool that is curved Path relative to a workpiece is moved. Examples are the application of pasty masses such as adhesive beads or sealing beads, welding, the soldering, labeling deburring, engraving.

The following explanations done on the basis of the economically important crawler control, in others Areas are the circumstances similar, the solutions easily transferable. First we treat controlling, then guiding.

Adhesive beads, Caterpillars, decorative caterpillars or other, by applying a pasty mass generated structures (short caterpillars) are working with two-dimensional, Gray value images processing image analysis systems optically controlled on correct position relative to the component and correct width. applications such as. Car window assembly also requires height control and the control of adherence to the geometry of a special Profile cross-section.

arrangements To do this use a sensor that is for width or position control consists of a camera and lighting, essentially in the highlight (angle of incidence = Ausfallwinkel) aligned with each other. For the height or profile cross-section control is currently preferred Light-section method (triangulation using structured light), e.g. one or more laser lines and a camera that reflected that Light detected. For "online" control, so for control during order, the sensor is mounted near the application nozzle and is i.a. firmly attached to this.

The applicator moves with the job relative to the workpiece on which the bead is applied is, it is basically indifferent, whether the nozzle with fixed workpiece moved or vice versa.

The Camera must be at The online control is directed to the area behind the application nozzle be. When curved Order tracks must the Sensor around the application nozzle be turned to constantly the area behind the application nozzle to be able to capture. When applying profiled caterpillars, the rotation is required anyway. When moving the nozzle through a robot can take over the rotation; at fixed Nozzle and by a robot moving part, although the robot can take over the rotation, but that can be great Divide, as they e.g. occur in the car body, take up a lot of space; If you want to reduce the space required, you need an extra turning device. Also, together with an extra turning device in many cases instead Simple and inexpensive x-y systems can be used by robots.

An extra turning device should be avoided for reasons of expense. For example, with the topic DE 203 07 305 U1 described that a monitoring device with one or more cameras on the tool is fixed so that the field of view of the camera (s) is always aligned with a movement of the tool and / or an object to be processed on the work area and / or a fixed surveillance area (claim 1). With a plurality of cameras on a circle concentric with a cutout for the tool, a substantially circular monitoring area can be achieved, which is formed by the viewing areas of several cameras. Thus, the monitoring area is substantially independent of the orientation of the tool (page 4 below, claim 2). Monitoring around the tool requires, according to this disclosure, at least two cameras with overlapping workspaces / monitoring areas.

A for all around Control suitable arrangement with only one camera is not specified.

The same solution with several cameras can be found in the disclosures WO 2005/065844, WO 2005/063406, WO 2005 /, 063407. Each time must, in order to achieve a surveillance area around the workpiece to be worked with at least two cameras (preferably three), see, for example, in the last three mentioned writings each 3 and 4 with explanations; a rotation is avoided: the surveillance areas keep their alignment.

disadvantage the arrangement is that several Cameras are required whose images i.a. even at the same time have to be evaluated In particular, the high space requirement associated with the arrangement is transverse to the direction of movement of disadvantage; the latter is a hindrance when the caterpillar in confined spaces (for example, along steeper Profiles) to be laid; that also comes in other applications quite before. In such cases can even if no collision with a camera is to be feared, Lighting technology to interference come through shadowing. Furthermore the arrangement is suitable only with very many cameras for a height control, if at all.

When guiding the tool through an optical sensor, eg when following an edge, a groove, a weld, also for punctually adjusting the movement based on "landmarks" like holes or edges, exactly the same problems occur as previously described for the optical control: in order to avoid a rotational movement in a curved path - with large differences in direction - a plurality of guide cameras are required in the prior art.

task The invention is to avoid these disadvantages.

The Task is solved after the independent Claims.

For optical control of the work result of a tool and / or for optical guidance of a tool 3 by means of a camera with an optical system, wherein the tool is relative to a workpiece 1 is moved in particular on a curved path,
is being proposed,
that the tool at least approximately centrally in the image field 8th located, and that its holder 6 within the beam path either at least approximately centrally in the beam path or directly in a pupil 15 the optics 10 . 10a . 10b or at least as close to a pupil of the optics that the holder is not displayed or so blurred that the work area 8th can be displayed as evaluable around the workpiece.

pupil is the aperture (e.g., aperture stop) of an optical system. at quite simple lens systems, the lens itself is the pupil. For more complex systems, e.g. at Köhler's beam path the aperture is depicted in real intermediate pictures. Pupil in the sense of claim 1 is the location of the effective aperture or the location of a Picture of it. For example, in a telescope, the exit pupil is a picture of the aperture in the front optic (aperture). Annotation: Not meant is the entrance pupil of a lens as a virtual Image of the aperture behind the front lens when the distance from Aperture to front lens is smaller than its focal length, the Front optics in this regard So how a magnifying glass works.

The Tool (the application nozzle in the example) is located at least approximately in the center of the Beam path. The holder runs through the beam path and is located on this path either at least approximately in the center of the ray path or in a pupil or near a Pupil. What kind of the holder applies, also applies to an energy supply (electricity, air pressure, ..) or material supply (adhesive, Welding wire, ..), if necessary; an energy or material supply can simultaneously Be a holder.

ever according to detail geometry, the holder (possibly also energy / material supply) either not shown or out of focus, or partially not and partially blurred; the blurred image superimposed the normally sharp image of the image field. In this case, the overlay go so far that that to be evaluated image field just by means of an automatic processing can be evaluated in the sense of the task.

The solution will first be described by the example of "crawler control" and by a simple lens which is also the pupil of the imaging system, see 2 , On the workpiece 1 becomes a caterpillar 2 applied with a tool 3 , here the vertical tubular applicator for the adhesive bead, with a nozzle 4 at the bottom. The material supply happens at the point 5 (Arrow) in the horizontal part 6 of the pipe. The horizontal part 6 is at the same time holder. for the vertical part 3 of the tube, which, depending on the application and view, can optionally be considered as a tool or holder for the tool. The tool is moved relative to the workpiece during the adhesive application, when in the image to the right (solid arrow), the caterpillar to the left of the tool in the with 2 indicated position, if in the picture to the left (dashed arrow), in the position indicated by dashed lines 7 , The caterpillar is placed in a field of view with the arrow 8th is indicated on a picture with the arrow 9 is hinted about optics 10 (Lens). The picture 9 may be on the surface of the camera sensor array 11 as shown, or it may be an intermediate image that is mapped to a camera sensor array via another optic (not shown). The tool 3 Located approximately centrically in the field of view of the camera, it is deliberately slightly displaced in the direction taken by the mount 6 points away (see below). The optics 10 is drawn for illustration technical reasons as a flat disk, as is the case when using a zone plate, but may generally be a lens or a lens system. The holder 6 is according to the invention in optics, which is identical here with the pupil in a simple lens. This ensures that the holder in the picture 9 does not represent at all or almost. If the holder is just behind (in the picture above) or in front of (in the picture under - preferred) the optics, the picture will slightly cloud one side 9 , at the dull or pointed end of the arrow of the picture 9 , Such a slight one-sided haze can be compensated by conventional image processing methods such as shading correction. The above-mentioned deliberate displacement of the tool from the center of the optics is used to compensate for the brightness to reduce the one-sided haze. Despite the cover of the optics 10 through the holder 6 the complete image around the tool is imaged, as indicated by the dashed imaging rays, because a point becomes imaged not only by rays in the plane of the drawing (these are partially blocked by the holder or the workpiece GE), but also by obliquely in the plane of the drawing or out of the plane extending rays.

In a particular embodiment, a coaxial illumination is realized through the optics, with a semitransparent mirror (or beam splitter cube ..) in the space between optics 10 and sensor array 11 , as is known from industrial image analysis. This achieves compliance with the gloss condition at a narrow illumination and viewing angle (without figure).

A particularly elegant illumination according to the invention consists of a lighting, which is located in or near the pupil. If the lighting consists of individual punctiform light sources, two light sources suffice 18 , if necessary, about the optics (see below 6 ), approximately to illuminate the area around the workpiece approximately coaxially. Since the light sources (including power supply) are at least approximately in the pupil, they are not or only very blurred. This makes a particularly slim design of the overall system with illumination in the glancing angle possible.

Of course you can also realized a conventional lighting outside the optics be, for example, as a ring light around the optics, in particular also supportive to the above arrangements, lower sensitivity against different workpiece tilt angle to reach.

In a particular embodiment, the arrangement is supplemented by a device 12 for cone-shaped lighting with a light edge 13 or a slit of light 13 , around the workpiece, see 3 ; Thus, a 3D evaluation of the bead can be realized, as previously known for straight crawler tracks or devices with mechanical rotation. Of course, the cone does not have to be circular, but can for example be a closed poly gon of straight, possibly slightly overlapping laser lines.

For the simple lens optically not optimal, but preferred for many practical applications leadership of the holder just before the optics (no manipulation of commercially available optics required) is in 4 shown. A contrast improved solution is obtained when at about this geometry of the holder 6 lies in a real pupil outside the optics. Such constructions are basically possible, see eg the telescope optics or - in another context - DE 103 20 165 A1 ,

A more space-saving variant with a bent material supply shows 5 , With less curvature of the material supply can, as in this figure with the dashed lines 14 implied, also an oblique course of the holder can be realized by the pupil.

An advantageous variant shows 6 : here is how in 2 the holder 6 exactly in the pupil of the optics, however, the arrangement is technically easier to realize: the optics 10 consists of two partial optics 10a and 10b (possibly simple lenses), in between, preferably in the middle, is the pupil 15 , The optics 10a and 10b Taken together, they act as an imaging system of image field 8th on picture 9 , Since the holder is exactly in the pupil, it is not displayed, not blurred. To produce only the front lens in the middle to be pierced, a cut out of the front lens with more complicated shape (as after 2 ) is not required, nevertheless the holder is located 6 exactly in the pupil.

The supply of material must occasionally for structural reasons or process reasons only via a straight or only slightly curved, ev. Even as short as possible tube (heating ..) happen. In particular, depending on the application to take into account that a metering device 16 possibly take up a lot of space. As a solution, it is proposed that the imaging beam path to 1 over a mirror 17 is kinked. The feed tube is not (or only slightly) kinked and passes through a hole in the mirror. In 1 leads the feed tube as in 6 also through a hole in the front optics 10a , The right part of the pupil 15 out 6 gets down into the plane 15b mirrored; the pupil lies in the half-planes 15a . 15b , The holder 6 is located in the beam path from the bottom, in the center of the beam path; in the beam path seen from the left in the pupil 15b ("right / up / down" figure-related). Alone in the paper plane blocked the holder 6 the view on location 7 , Location 7 however, is sharply defined by rays oblique to the plane of the drawing.

Of course they are constructive depending on the feed material (e.g., welding wires) and geometric boundary conditions also entprechende mixed solutions possible with slightly curved Material supply and "half" kinked beam path.

In the experience of the applicant, the realization of the entire beam path simplifies considerably when the image of the optics 10 respectively. 10a / 10b leads to an intermediate image, which is captured on a screen and a further optics on the sensor array 11 is shown in reduced size. Classically, one works on intermediate images without the ground glass. In contrast, the solution with a screen is less bright, the overall look but builds considerably smaller.

A solution after 6 or 1 , but without piercing front optics 10a , you get with a lens with real entrance pupil in front of the optics 10b as above 4 explained.

Another alternative is to insert a mirror like 6 , but in a real pupil in front of the front optics 10 respectively. 10a (without figure).

The Of course, this arrangement does not only work for beading but also for others Applications, as exemplified above. In a welding or Soldering System can be a material supply in principle As shown in the figures are realized here, of course, the little preferred curved solutions and those that do not pass through an optic have to. A holder with power supply (spot welding, roll welding ..) can in or near a pupil, in or near the optic star-shaped (attachment on radial outward walking bars) will be realized. For Tasks without electricity and material supply would basically be the same conceivable, the tool without extra bracket directly in the center of the Attach optics.

tasks the optical guidance can be solved with exactly the same arrangements. Thus, e.g. a curved one Traced workpiece edge along which a sealing bead is to be laid, without the orientation of the workpiece or the sensor to change. This is especially valuable with closed contours. With the same arrangement can be the management task and the control task can be realized without an extra turning device to need.

A Another application is the guide to precise Gripping or joining of components. The tool here is a gripper (suction gripper, Spreizgreifer ...) or to be joined Part (e.g., bolt, here representing the tool) used in e.g. a hole in the workpiece insert is. Since the image field with the tool is carried relative to the workpiece, if you can work with a small image field, you always have a workpiece and a tool with high resolution in view, all around the tool and looking perpendicular to the workpiece (no distortions due to oblique view), with all associated metrological Benefits. With the arrangement described here, if necessary, regulated, so by visual servoing (workpiece and tool constantly in Look), a workpiece exactly gripped or a part be joined.

The Camera has a connected or integrated image evaluation unit, as common in industrial image processing.

Advantages:

It if only one camera is used (price, space required), the viewing beam is narrow. In koaxia ler lighting and the illumination beam is narrow. The construction is narrow in all lateral directions, especially with closed contours and at least in places steep workpiece profiles or bottlenecks (no / less collision problems, no shadows).

The Switching between cameras for many practical applications Required simultaneous evaluation of multiple cameras is eliminated. The is especially important in online evaluation, because here speed is asked.

Of the Advantage of the particularly slim design of the lighting and Viewing beam path, around the tool, of course, also comes with Non-curved applications Train to carry, especially in the case of and / or control tasks in confined spaces.

The 3D analysis based on cone-shaped lighting can be combined be using a 2D evaluation based on one of the other illumination methods, preferably for the separation of the evaluations in the time multiplex (switching of the illuminations) or in color multiplexing (using a color camera chip and different wavelengths for the different Illumination types) is worked.

It applications are possible in which leadership, Editing and control in a single operation with only a camera can be realized e.g. the fine-tracking of a (possibly roughly given) joint, whose Sealing with sealing material and the immediate control of the applied sealing material, possibly with regulation of the material supply parameters on the basis of the measured Control values.

The Arrangement can also be advantageous for gripping or joining means Visual Servoing be used.

Claims (9)

Arrangement for optically controlling the work result of a tool ( 3 ) and / or for optical guidance of a tool by means of a camera with an optical system ( 10 . 10a . 10b ), wherein the tool relative to a workpiece ( 1 ) is moved in particular on a curved path, characterized in that the tool at least approximately centrally in the image field ( 8th ) and that its holder ( 6 ) within the beam path either at least approximately zen in the optical path or directly in a pupil ( 15 ) of the optics ( 10 . 10a . 10b ) or at least as close to the pupil, that the holder is not displayed or so blurred that the work area ( 8th ) is displayed evaluable around the workpiece. Arrangement according to claim 1, characterized by location the pupil in front of the front lens. Arrangement according to claim 2, characterized in that in the pupil a mirror ( 17 ) is located, over which the imaging beam path is bent. Arrangement according to claim 1, characterized by an optic of two parts ( 10a . 10b ), between which the pupil is located. Arrangement according to claim 4, characterized in that in the pupil a mirror ( 17 ) is located, over which the imaging beam path is bent. Arrangement according to one of the preceding claims, characterized by illumination ( 18 ), which is located at least approximately in a pupil, preferably consisting of at least two at least approximately point-shaped light sources. Arrangement according to one of the preceding claims, characterized by coaxial illumination through the lens, introduced by means of semipermeable Mirror. Arrangement according to one of the preceding claims, characterized by a device for cone-shaped illumination ( 12 ) with a light edge ( 13 ) or a light slot ( 13 ), around the workpiece. Method of joining or gripping, characterized by visual servoing using an arrangement as described in one of the aforementioned device claims.